Integrated optical components of the kind referred to above are known especially as star couplers in combination with arrayed waveguide gratings, such as for configuring multiplexers and demultiplexers. Examples of such star couplers and a method of making the same are presented in U.S. Pat. Nos. 5,412,744 and 5,414,548.
International Patent Publication WO 95/13553 discloses a method of making integrated optical components having buried waveguides in glass. These components are made utilizing an ion exchange with a mask. This publication also describes the making of a transition between two waveguides which are embedded at different depths. The transition is made utilizing a diagonally cut mask only partially exposing the waveguides.
The mask used reproduces the desired free spaces with an expanded layer waveguide simply as a free space. The problem present utilizing such a mask is that the refractive index profile is deeper in this region than for the narrow strip waveguides which communicate therewith. This is not usable because of the high attenuation.